Variable-load brake



T. H. THOMAS VARIABLE LOAD BRAKE Filed July 7, 1926 May 22, 1928:

Y ww 9 ll//lll//A VII/ln VII INVENTOR THOMAS H THOMA @fm/@M ATTORNEY Patented May 22,1928.

r 1 UNlrEDIsTATyEsf p'rnoms n. "TBomAs,`or nnenwoon PENNSYLVANIA Assreivoia To THE WEsTING-j `rrousn lAm BRAKE COMPANY, or WILMERDING, PENNSYLVANIA, A conroRlA- TIoN or PENNSYLVANIA.

VARIABLE-LOAD BRAKE.

` Appnmqnmed July 7, 1926. serial No. 120,939.

[This invention relates to variable load brake devices and 1s more particularly in the nature of an improvement on the Varlable load brake device' described in my pend- 6 ing application, Serial No. 79,549,1filed an#y Vith the construction shown in the above application, graduated' release is effected i by t e use of a timing reservoir While according to the present application, `means vare pro vided, whereby t e `releaseis graduated in proportion to theload on thecar. In the accompan ing drawing;

diagrammatic sectional view of' a variable load brake apparatus embodying my inven` tion; and Fig. 2 a View` of the mechanism by i ingeneral, quite similar to that ofmy pending application hereinbefore referred to and comprises a casingl having al vertically disposed piston cylinder 2 containinga piston 3 having a piston stem 4 which slides ina borebf reduced*` diameter. In the bore 5 is disposed a dash pot piston 6 and interposed between said piston and the end of the stem 4 is a coil" spring 41. l

A lever 7 is connected to piston stem 4 through a link 8 and a lever 9 is pivotally connected to thefree end of lever 7 by means of a pin 10. The o posite end of lever 9 is `secured to a rotatab e pin ll'and an arm 12 is also secured to said pin. The arm 12 is connected to a rod13 which in'turn is pivotally connected to af rocker arm `14 carried `by the lcar body. A member 15 carried by the car truck is ositioned to be engagedby the free end of t 1e rockerfarm 1 5.

A lever 16,'i'ulcrumed on a fixed pin 17 is connected at one endA to a link 18 carrying a roller 19 at its free-end and the opposite end of the lever 16 is connected` through a link 20 to the piston 6. An arm 21 `is carried by the lever 16 and is providedat its free end with a toothed segment 22.

` Fulcrumed on `a pin 23 is a rocker arm having a pavvl yarm 24 provided With teeth yadapted to engage the teeth of the segment 22 and having an arm25 which is connected to the stem 26 of a piston 27, contained in piston chamber 28. Leverlf7 is also connected to `lever 16 by a link63.'`

v Vertically disposed in the casing 1 are Fig. 1 is a flexible diaphragms730 and `31,1the dia phragm 30 being engaged onoIie side by a follower plate 32 having a stem 33 Which engages a fulcrum plate 34, andthe Vdiaplate 34 is pivotally supported by a`linlr37` which `is pivotallymounted on the pin 23 and roller 19 is interposed betvveen the Vface- 38 of theplate 34 and a face of a member40 carried by the casing 'y Thestem oi avalve 42 engagesthe side of .diaphragm 31 opposite the follower 35,\said valve being subject to the pressure "of fal lspring 43 tending to seat the valve. y 4

A relay valve portion 44 is provided' having a piston chamber 45 containing a piston L46 anda valve chamber 47 containing a slide valve 48 adapted to be-operated by' said piston through a stem 49. AA small piston 50 is` provided on stem 49 intermediate the pis-` ton 46 and the valvey48 anda guide piston 51 is carriedby said stem at its outer end.v

Avalve 52 is'positioned to beoperated by the inward movement of the stem 49 and controls the supply of fluid under: pressure from valve chamber 53 to` a pipe 54Whichleads to the brake cylinder (not shown).

The fulcrum plate 34 `isprovided with an arm or lug-55 and'c'arried'by said arm is an adjustable screw 78 for operating the phragm`31 beingengaged `on one side bya stem of a pilot release valve 56A for controlling the venting of fluid under pressure,-

from piston chamber V45 through passage 57 to an atmospheric exhaust port 58.`

The piston chamber 2 is connectedthrough passage 59 with af pipe 60 Whiclris connected` to thecar door opening pipe, said,`

theflever 16 "is locked against movement by the engagement of pa'vvl arm 24 with the toothed segment 22 of arm 21, thepin '62 which connectslink Vwith' said lever acts as a fulcrumpand the movement of 'lever about said fulcrum causes a movement of rod 13 to the left, through the movement of thefarms .9 and; lf2. y

The rocker arm 14C is thus actuated `to cause the free end to engage the member 15.

After the above movement of part-s, the piston 2T is shifted outwardly,so that "the paivl arm 21 is actuated to ydisengage the teeth of the pawl from the teeth of the toothed segment 22.

:'Ihe rod 13 vis now `free to 1move jaccordingto the load @n.the Car. `Ifthe load is increased, the carbody will move toward the fcar `truclcand thuscausethe member '15 toroclr the rocker arm 14 andefi'ectaeorrespondingmovementlotthe rod 13 toward the .right .Piston 3 holds `the yadjacent; end of the lever 7 Aagainst vertical `movementand .the leverl being .fulcrnmed on the `pin 17, the movement of the rod 13 toward the right causes a counter-clockwise movement 'of arnr9 andthe lever 7. TheQlin-k 63 isfthus moveddownwardly and causes acounterclock-wisemovement of lever 1G aboutxits fulcrum pin 17, soithat thelink 18iis,pulled downwardly, causing 4a doxvnward .movement of kthe fulcrum `roller 1S). Thus the position of theroller19 is ,determinedad cording togthe load on the car. :Ithevload is-decreased, the .parts Will.1nove,in;the reverse .directiomiaswill be evident, .and the roller 19 will be caused-to move upwardly.

' When vthe vcar -is to :be started,` the car doors .are closed and fiiuid yunder rrpressure is yvented from pipe 4.60 and passage ^59. Since .the spring 61 exertsa. greater .'pressure than spring `41, the release of `fluid under pressure from ,passage 59 :first permits'the piston E27-to befshifted-by spring 61, so that the pawl arm 24 isoperated to cause the pawl teethito-engage the .teeth'of the segmentZQ. 'The zii-m21 is thuslockedagainst movement While thecar `is running. Y

Piston'S-then returns .to its normal posi tion, causing the rod `13 tobepulledtoward the right, so that the lfree end of the rocker arm 14 is moved out of engagement Withfthe member 15, thus preventing movement of the parts by .the relative .movement ofthe carfbody with respect to the truck, .so long us'the car is running.

The piston being connectedto lever :16 aumes. a position-in the bore 5, corresponding with the position of the roller 19.

k',VVhen `the brakes are applied in `making a carstop, .the triple or other brake controlling valve device is yoperated to supply llui'd undeixpr'essure to arvolumeyreservoir or dummy brake cylinder, 64, which is connected through pipe 65r and passage 66 with one side .of .the .diaphragm 30. 4The ,diaphragm 30 is then moved-outwardlycausing the stemt'BB to move" the plate34 with Apassage G8 and pipe.69to avsoureerof-ffluid under pressure,-sueh l as `the.mai n reservoir, so that when valve l2 1s opened, Huid under pressure isy supplied to passage 57, leading to piston chamber 45. Piston 46 is then shifted tova'rd 'the right, so that slide valve 48is tirstoperated .to close therexhaustports 7() and thenthe piston stem 49 engages'the steml of valve 52. The valve 52 ist en unseatedand `tluid `under vvpressure is supplied from lchamber `53, which `is. connected `to `the main reservoir passage 68, to lpassage 71V, which leadstothe 4brake ,cylinderI ipe 54.

llVhenrthe pressureacting on uaphragni 31 has been increased by 'fi0w,pastthc valve 12,10 a degree suchas .toslightly exceed the pressure acting ondiaphragmBO, and taking into account theyposition `otthefulcrum roller 19, the diaphragmclxwillcmove so as.` to permit vthe valveeQ to close. y`I `luidistlu1s supplied to ipiston4 chamber A4:5. and isbottled up `by theclosing ot valve .42,atazr pressure corresponding with thceload `on ,the car.

Fluidfsupplied tothe brake cylindeigiis also supplied throughlpassage 72 and agrestrictedl port 73 to the chamber ,between the pistons A6, and. 50, and .when the ,pressure vin said chamber has beenincreased `to ,a .degree corresponding 1.with the pressure -.in piston chamber 145,the ,piston elisunoved sokasito permit the .valve .52 fto close. The `pressure of yfluid supplied ,tocthebralie cylinder is thus proportional. .to .theg .pressure `of fluid in piston chamber fand consegpiently .to the yload.on:the car.

lheypressuredn,the bralrercylinderA maybe graduated on, by increasing the pressure i. oi' Huid `in the dummy brake cylinder y(il, throughthe voperation 10i' the usual .brake controlling valve device. y

In releasing the brakes, vif the. fluid Aunder pressure inthe dummybrakecylindelufl exhausted by operation of .the brakelcoib trollingl -valve device74 .thevpressure on diaphragm 30 is reduced, iso that .the fluid pressure acting? oit diaphragm 31 actsA on.thc plate lllsoras to rocksameiinaulirection-to open therelease pilot-valvez. Therapeuing Vof `pilot valve ."raiuses fluid under pressure to .be vented from lpiston `chamberw15, permitting the brakeieylmder ipressure act ing on the oppositesideiof the 'piston lo shift said pistonto `its release .posilion,; in whielrtheexhaust ports 70 are opento .vulve chamber 47, ythus permittiiug.fiuid under pressure `to be yexhausted from the brake cylinder.

A The brakesunay .be whollyl released, italie fluid under pressure in the. dummy bralzecvlinder 64 is .whollyexliausted byfoperation of the brake controlling valve device. If,

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however, the fluid in the dummy brake cylinder is partially released in order to effect a graduated release of the brakes, then the release valve 56 Will only be held open until the pressure in piston chamber 45 and on the diaphragm 31 has been reduced to a degree corresponding With the degree to which the pressure acting on the diaphragm 3() has been reduced. As soon as the release pilot valve 56 closes, further reduction in pressure in the brake cylinder permits the higher pressure in piston chamber 45 to shift piston 46 so as to` operate the slide valve 48 and close the exhaust ports 70. j i

It Will thus be seen `that the pressure in the brake cylinder will be graduated off in proportion to the load on the car and corre spending with the graduations in pressure in the dummy brake cylinder 64. j

`lfVhen the parts are in adjusted position, With the paWl arm 24 in locking position, the piston 6 isiin some position in bore 5, dependent upon the previous adjustment of the parts according to the load on the car. If, for any reason,the piston 27should move before the piston 3, then the release of the pawl 24 permits the spring 4l to throw the piston 6 downwardly and With considerable force against the cylinder head 75. In order to prevent such sudden movement ofl the piston G, said piston is provided with a piston ring 76 and through the piston a restricted port 77 is provided. By this arrangement, the piston 6 moves gradually, according to the rate fluid can escape through the port 77 and thus the piston is prevented from striking a sharp blow on the cylinder head.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is

l. In a variable load brake, the combination With a brake' cylinder, of a valve device for controlling the releaseof fluid from the brake cylinder, a valve for controlling said valve device, and mechanism adjusted according to the load on the car for operat1 ing said valve.

2. Ina variable load brake, the combination with a brake cylinder, of a valve device for controlling the admission and release of fluid under pressure to and from the brake cylinder, valve means for controlling the operation of said valve device, and mechanism adjusted according to the load on the car for operating said valve means.

3. In a variable load brake, the combination with a brake cylinder, of a valve device operated byvariations in fluid under pressure for controlling the admission and release of fluid under pressure to and from said brake cylinder, a valve for supplying fluid underpressure to said valve device, a valve for venting fluid under pressure from 'said valve device, `and means adjusted acsubject to the opposing pressures of the brake cylinder and a chamber for controlling the admission and release of lluid under pressure to and from said brake cylinder, valve means for controlling the pressureof fluid in said chamber, and means adjusted according to the load on the car for operating said valve means. i e

5. In a variable load brake, the combination with a brake cylinder', of a valve device subject to the opposing pressures of the brake cylinder and a chamber for controlling the pressure in the brake cylinder, a fulcrumed member, a flexible diaphragm operated by variations in fluid under pressure for operating said member, a valve operated by said member for varying the pressure of fluid in said chamber, and means operated according to the load on the car for adjusting the fulcrum of said member.

6. In a variable load brake, the combination with a brake cylinder, of a valve device subject to the opposing pressures of the brake cylinder and a chamber forcontrolling the pressure in the brake cylinder, a fulcrumed member, a flexible diaphragm operated by variations in fluid under pressure for operating said member, a valve operated by said member for varying thepressure of fluid in said chamber, a flexible diaphragni subject to the pressure of fluid in said chamber for also controlling the operation of said valve, and means operated according to the load on the car for adjusting the fulcrum of said member.

7. In a variable load brake, the combina-4 tion With a brake cylinder, of a valve device for controlling the release of fluid from the brake cylinder, a valve for operating said valve device, a fulcrumed member for open ating said valve, and means operated according to the load on the car for adjusting the fulcrum of said member'.

8. In a variable load brake, the combination with a brake cylinder, of a valve device THOMAS I-I. THOMAS. 

